In a food processor (yes a food processor - I said it was easy) add the flour, sugar and butter. Using the pulse button, mix until it acquires that breadcrumb like appearance.

The key to this pastry is making sure the water is ice cold. The downside of using a processor is that it "heats" the pastry - to combat this using the coldest water possible keeps the mix cold, so it amalgamates before it heats up too much and starts melting the butter.

The amount of water needed depends entirely on your flour, sometimes I can get away with 2 tablespoons, this last batch needed 6 tablespoons. I make the iced water by getting a small metal bowl (better conductive properties) and filling it with ice cubes and then pouring over just enough cold water to cover.

Just add the water one tablespoon at the time and pulse until the dough comes together. Take it out of the processor and knead it very lightly, just to make sure it's a nice smooth silky dough. Form a round, flatten it slightly then wrap in plastic and place in the fridge. Let it rest for an hour.